The broad objective of the proposed research is to improve the practice of preservation and transfusion of human red cells by learning more about the biochemical properties of red cells stored under current blood banking conditions, by looking for new ways to extend the storage life of the red cell and to improve its post-transfusion function in oxygen transport, by seeking means to better measure the effectiveness of transfused red cells for the treatment of tissue hypoxia, by trying to find out the nature of the biochemical changes in the different tissues of the body which are most critical for their survival during acute hypoxia, by seeing how these changes are reversed by transfusion, and by searching for agents which can supplement the red cell transfusion to hasten the reversal of tissue hypoxia, and so minimize its pathological effects. Emphasis will be placed on analyses of the intermediates of carbohydrate metabolism and related adenine nucleotides of human and rabbit red cells during storage in ACD and other preservative solutions. Physiological and biochemical effects of acute hemorrhagic hypoxia will be examined in rabbits. The effects of transfusion of rabbit red cells stored under different conditions will be studied in normal and hypoxic rabbits.